>> reporter: denise, the commissioner told us tonight that gun used was so small, you could fit it in the palm of your hand. now, the gunman had a concealed weapons permit for about the past four years in virginia. but he had no record of doing anything violent. and the commissioner doesn't believe he planned this either. >> one day after the terrifying lockdown at world-renowned johns hopkins hospital, new information is coming to light about paul partis, the gunman who shot his elderly mother's doctor, then killed her and himself. >> we don't know yet if it was in his daily routine, coming and visiting his mother that, he always had that gun. >> reporter: investigators say partis was distraught over has 84-year-old mom's prognosis, and used a 32-caliber, cal tech semi automatic handgun, like this one, to shoot dr. david cohen, who will survive. partis' gunman said -- neighbor said he will survive. >> i think he felt like he might have been partially responsible. >> partis had no criminal record. the incident rattled the nerves of those who are simply trying to get back to norm
